This invention relates to drill bits, more specifically to improvements in drill bits used for drilling in mine roof bolting operations.
Such drill bits are subjected to large torsional and axial forces, high rotational speed, heat, and abrasion. These environmental factors may cause wear on the cutting elements and the bit body. Long bit life is desirable to reduce the machine downtime required to replace the bit and the associated cost. Extending time between bit replacements may reduce the time spent by mine workers in dangerous, unsupported areas. Roof bolt bits have been disclosed in the prior art.
U.S. Pat. No. 5,535,839 to Brady, which is herein incorporated by reference for all that it contains, discloses a rotary drill bit having a head portion with at least two hard surfaced inserts having domed working surfaces and being oppositely oriented to face in the direction of rotation at positive rake angles, and a mounting adapter for removably securing the drill bit to a drilling machine.
U.S. Pat. No. 5,429,199 to Sheirer, which is herein incorporated by reference for all that it contains, discloses a cutting bit useful for cutting various earth strata and the cutting insert, which may be made from a polycrystalline diamond composite, for such a cutting bit. The cutting bit has at least one pocket at the axially forward end thereof which receives its corresponding cutting insert. The cutting insert has at least one exposed cutting edge which is of an arcuate shape.
U.S. Pat. No. 4,550,791 to Isakov, which is herein incorporated by reference for all that it contains, discloses a two-prong rotary drill bit, especially for use with roof drills. The two-prong bit has a supporting body having an axis of rotation. The two-prong bit has a pair of inserts, one insert on each of the prongs. Each of the inserts has a cutting portion facing in the direction of rotation and a mounting portion. When viewed in a direction parallel to the axis of rotation, each of the inserts will have a cross-sectional configuration which is generally wedge-shaped. Also disclosed are wedge-shaped inserts especially for use with roof drill bits.